This epidemiologic study examines the possible relationship between smoking, diet, and other health habits, and the risk of developing Parkinson disease. By using nested case-control methods, and cohort methods, we will evaluate all living and dead subjects in the 8,000-man Honolulu Heart Program cohort. We will link health status, as determined by the ongoing (1991 - 1993) rescreening of subjects, to histories of diet, smoking, and occupational/personal exposures documented at the program's inception in 1965. The information from this study should provide clues to the causes of, and the pathogenesis of Parkinson disease, including information bearing on the theory that Parkinson disease is an exaggerated or atypical form of the normal aging process in which free radical damage to neural cells results from various metabolic, toxic, genetic, or dietary causes. The study may also suggest avenues for further research and interventions to prevent Parkinson disease, or to delay its progression, by dietary and lifestyle measures.